By using a blue or green screen, we’re talking about bringing subjects into a virtual background using the chroma keying technique. Chroma keying allows a specific colour element in a production shoot to be removed and replaced with a distinct, new digital background. Often used in the Newsroom for the weather report and in many Hollywood movies such as hit movie – The Avengers, and the top grossing movie – Avatar. The use of the blue/green screen and the chroma key technique has allowed producers to broaden the scope of special visual effects to create something exciting and unique that cannot be produced in reality.
However, to achieve the perfect blue/green screen, these are 5 key points that are important to take note of:
- It is important to make sure that the colour of the backdrop is not similar to the colour of the subject in the frame so that the subject does not get blended into the background. This is why a bright shade of blue or green is commonly used as the background screen.
- Smooth the blue/green screen as much as possible. This can be done by physically stretching the screen or hanging it so that the weight of the screen will pull it down.
- Create a soft, even light over the blue/green screen. If the lighting is not even, there will be hotspots and shadows on the blue/green screen and the perfect keying will not be obtained. Kino lights are a good option to consider when deciding on the type of light to be used.
- Treat the blue/green screen and subject separately. Adjust the lighting of the blue/green screen first. After the lighting of the screen is satisfactory, move on to adjusting the lighting of the subject using a different set of lights.
- Shoot at a close aperture so that the subject will appear to be sharp.
The blue/green screen technique here has been used to create motion graphics, a digital technique that combines various aspects of film, animation and graphic design, but it can also be used to create 3D animations so as to create a dynamic and compelling piece of digital footage.